Why Invoke() works on .NET framework delegates and not on my own????

Why doesn't this code compile??? Why can I call Invoke on .NET Framework defined delegates and not on my own. using System; namespace DelegatesTest { public delegate void MyDelegate(); ///

/// Summary description for MyClass. ///

class MyClass { public System.Threading.TimerCallback timerCallback = null; public System.Timers.ElapsedEventHandler elapsedEventHandler = null; public DelegatesTest.MyDelegate myDelegate = null; ///

/// The main entry point for the application. ///

[STAThread] static void Main(string[] args) { MyClass myClass = new MyClass(); // OK myClass.timerCallback.Invoke(null); // OK myClass.elapsedEventHandler.Invoke(null, null); // NOT OK - will not compile myClass.myDelegate.Invoke(); } } } Don't look at the fact that the 3 delegates are not assigned any valid method ... I tried writing the shortest possible example to explain my problem. Bob